Plasmonic Properties of Periodic Arrays of Ag Nanocylinders and Dimers, and the Effects of an Underlying Ag Layer

Despite the progress in understanding the properties of plasmonic nanostructures, the design of structures with specific optical characteristics still poses a challenge. To better understand how material and various geometrical parameters affect the response of the nanostructures, we analyzed, theoretically and experimentally, the optical properties and their tunability in diverse configurations of a two-dimensional periodic array of silver nanocylinders and dimers, with or without an underlying thin silver layer. We show the tuning of the surface plasmon resonances can be approximated by affine equations at the regions we worked on. The controllable parameters that can be used for tuning include nanoparticle-metal layer distance, index of refraction of the surrounding dielectric material, cap layer thickness, and cylinder diameter. We also calculated the enhancement of the average square electric field at the top surface, useful for surface-enhanced spectroscopies. Enhanced optical transmission not due to propagating surface plasmon was also observed.